In an effort to satisfy complaints about aircraft noise in and around airports, the FAA has set forth noise reduction requirements. New aircraft, with the noise requirements in mind, can be designed to meet the standards, however, there is a substantial fleet of airplanes, and in particular Boeing 727 aircraft, which were manufactured prior to the requirement which do not meet the noise standards. Previous efforts known to the inventors to reduce engine noise on an airplane similar to the 727 include U.S. Pat. No. 5,127,602 which combined the structural modifications of an exhaust mixer to mix fan air with the turbine exhaust through the use of a fluted disk, along with an increased spacing between the inlet guide vanes and the inlet fan blades to generally reduce engine noise during landing. Of course, this required some modifications to the cowling.
Further, in an attempt to improve aircraft performance, the tips of the wings of the 727 were modified by adding winglets as described in U.S. Pat. No. 5,471,153. This wing tip modification in combination with altered flap and aileron positions increased the fuel mileage and decreased the drag, allowing the airplane to operate at greater, more efficient altitudes.